The present invention relates to a recording head position adjusting structure which adjusts the position of a recording head against a recording head mounting portion of a printer main body. Further, the present invention relates to an inkjet printer provided with a mechanism to perform position adjustment of the recording head.
Heretofore, an inkjet printer, which forms an image on a recording medium by ejecting ink onto the recording medium by use of a recording head, has been brought into practical use. To easily mount a recording head on an inkjet printer main body or to replace a recording head having finished the life by a new one, a recording head is mounted on a printer main body by means of assembly and a recording head is provided on a printer main body freely removable.
When a recording head is not mounted at an appropriate position, image displacement or a fuzzy image may be caused. Therefore, to mount a recording head at an appropriate position is important for excellent image formation.
For example in patent literature 1, described is a recording head position adjusting mechanism which adjusts the recording head position against a carriage of a printer main body. In this position adjusting mechanism, a recording head is mounted on the flat plane of a carriage and a plane inclined against said flat plane of the carriage is provided on this recording head. A screw, the head of which is press contacted with the inclined plane, is engaged to the flat plane of a carriage. When a screw is rotated to one direction by a user, the head of the screw is transferred to the direction of approaching to the flat plane of a carriage to press the inclined plane of a recording head, resulting in transferring the recording head along the flat plane toward the direction leaving from the screw. On the other hand, when a screw is rotated to the reverse direction by a user, the head of the screw is transferred toward the direction leaving from the flat plane of the carriage, resulting in enabling to transfer the recording head along the flat plane toward the direction approaching to the screw.
[Patent literature 1] JP-A No. 2001-113679 (Hereinafter, JP-A refers to Japanese Patent Publication Open to Public Inspection)
However, dimensions such as the position and inclined angle of the inclined plane may be varied due to errors depending on individual recording heads, which requires more precise design and manufacturing of a recording head to avoid dimensional errors of the inclined plane. Further, without performing precise design and manufacturing of a recording head, it is necessary to confirm the dimensional errors of the inclined plane to mount the recording head at an appropriate position; however, it is not easy to confirm the dimensional errors of the inclined plane.
Therefore, this invention has been made to solve the above problem and an objective of this invention is to provide a head position adjusting structure which permits mounting of a recording head at the appropriate position even without performing precise designing and manufacturing of a recording head.
Further, many inkjet printers have been utilized because they, generally, generate relatively small noises at the time of image recording and exhibit excellent image recording quality. As the aforesaid inkjet printer, there is, for example, a serial type in which a carriage, on which a plural number of recording heads are mounted along the main scan direction perpendicular to the transport direction of a recording medium, is transferred along said main scan direction and an image is formed by ejecting ink through the nozzles of recording heads while said carriage is transferred. Further, in recent years, proposed has been an inkjet printer which performs high speed and high quality image recording by arranging plural number of recording heads for ejection of each color ink.
To perform high precision image recording with such a serial type inkjet printer, it is necessary to accurately eject ink from the aforesaid plural number of recording heads while transferring the aforesaid carriage, which requires precise position adjustment between each recoding head. In particular, in the case of plural recording heads, which eject the same color ink, being provided and image recording is performed by regarding the plural recording heads, which eject the same color ink, as purely one recording head, there is a problem that generated is such as color unevenness, in which a certain portion is deep colored and another portion is light colored in a recorded image, resulting in difficulty of performing high precision image recording, when the nozzle positions do not coincide due to a position deviation between recording heads. Therefore, it is necessary to perform very precise adjustment as minute as ± few μm with respect to the position along the transfer direction of each recording head, which ejects the same color ink, so as to precisely adjust each recording head position to make the nozzle positions coincide.
With respect to this point, conventionally known has been an inkjet printer in which the positions along the main scan direction and transfer direction are adjusted by two adjusting screws from different directions being press contacted with a recording head and the pressing power against the recording head is adjusted by rotating each adjusting screw (for example, refer to patent literature 2).
[Patent literature 2] Japanese Patent Publication No. 3-76834
However, in the case of adjusting the positions of a recording head along the main scan direction and transport direction by use of two screws, since the position along the main scan direction having been determined in advance may be shifted at the time of successively determining the position along the transport direction even when the position along the main scan direction has been once determined, it is necessary to repeat minute adjustment many times to accurately determine the positions along both of the main scan and transport directions, resulting in a problem of tediousness.
Further, in the case of position adjustment is performed by a screw, the precision of adjustment is limited by the pitch of a screw groove formed on the circumferential surface of a screw. It is necessary to utilize a small screw to perform more precise adjustment, because the smaller is a screw, the more minute is the pitch of a screw groove. However, there is a problem that the thickness of a screw becomes slim as an adjustment screw becomes the smaller, resulting in being impossible of maintaining the strength as well as difficult operation for a user who performs adjustment action of the recording head.
Therefore, the present invention has been made to solve the above problem, and an objective of this invention is to provide an inkjet printer which enables to perform easy and accurate position adjustment of a recording head even in the case of employing a plural number of recording heads for the same color.